// SPDX-License-Identifier: GPL-2.0
#include <seminix/param.h>
#include <seminix/memblock.h>
#include <seminix/mm.h>

static u64 patterns[] __initdata = {
    /* The first entry has to be 0 to leave memtest with zeroed memory */
    0,
    0xffffffffffffffffULL,
    0x5555555555555555ULL,
    0xaaaaaaaaaaaaaaaaULL,
    0x1111111111111111ULL,
    0x2222222222222222ULL,
    0x4444444444444444ULL,
    0x8888888888888888ULL,
    0x3333333333333333ULL,
    0x6666666666666666ULL,
    0x9999999999999999ULL,
    0xccccccccccccccccULL,
    0x7777777777777777ULL,
    0xbbbbbbbbbbbbbbbbULL,
    0xddddddddddddddddULL,
    0xeeeeeeeeeeeeeeeeULL,
    0x7a6c7258554e494cULL, /* yeah ;-) */
};

static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
{
    pr_info("  %016llx bad mem addr %pa - %pa reserved\n",
        cpu_to_be64(pattern), &start_bad, &end_bad);
    memblock_reserve(start_bad, end_bad - start_bad);
}

static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
{
    u64 *p, *start, *end;
    phys_addr_t start_bad, last_bad;
    phys_addr_t start_phys_aligned;
    const usize incr = sizeof(pattern);

    start_phys_aligned = ALIGN(start_phys, incr);
    start = __va(start_phys_aligned);
    end = start + (size - (start_phys_aligned - start_phys)) / incr;
    start_bad = 0;
    last_bad = 0;

    for (p = start; p < end; p++)
        *p = pattern;

    for (p = start; p < end; p++, start_phys_aligned += incr) {
        if (*p == pattern)
            continue;
        if (start_phys_aligned == last_bad + incr) {
            last_bad += incr;
            continue;
        }
        if (start_bad)
            reserve_bad_mem(pattern, start_bad, last_bad + incr);
        start_bad = last_bad = start_phys_aligned;
    }
    if (start_bad)
        reserve_bad_mem(pattern, start_bad, last_bad + incr);
}

static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
{
    u64 i;
    phys_addr_t this_start, this_end;

    for_each_free_mem_range(i, MEMBLOCK_NONE, &this_start, &this_end) {
        this_start = clamp(this_start, start, end);
        this_end = clamp(this_end, start, end);
        if (this_start < this_end) {
            pr_info("  %pa - %pa pattern %016llx\n",
                &this_start, &this_end, cpu_to_be64(pattern));
            memtest(pattern, this_start, this_end - this_start);
        }
    }
}

/* default is disabled */
static unsigned int memtest_pattern __initdata;

static int __init parse_memtest(char *arg)
{
    int ret = 0;

    if (arg)
        ret = kstrtouint(arg, 0, &memtest_pattern);
    else
        memtest_pattern = ARRAY_SIZE(patterns);

    return ret;
}

early_param("memtest", parse_memtest);

void __init early_memtest(phys_addr_t start, phys_addr_t end)
{
    unsigned int i;
    unsigned int idx = 0;

    if (!memtest_pattern)
        return;

    pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
    for (i = memtest_pattern-1; i < UINT_MAX; --i) {
        idx = i % ARRAY_SIZE(patterns);
        do_one_pass(patterns[idx], start, end);
    }
}
